Automatic Speed Control Apparatus for Treadmill and Control Method Thereof

ABSTRACT

The present invention provides an automatic speed control apparatus for a treadmill and the control method including a deck, a track belt of endlessly rotating on the upper and the bottom face of the deck, and a driving unit for driving unit for driving the track belt comprising: at least one front load sensor located in the front part of the track belt for measuring load from a user on the track belt; at least one rear load sensor located in the rear part of the track belt for measuring load from the user on the track belt, wherein the proceeding speed of the track belt is controlled based on the user&#39;s location or movement on the track belt by comparing the measured values from the front load sensor and the rear load sensor and catching the user&#39;s location based on the comparison therebetween, whereby the proceeding speed can be automatically controlled corresponding with the user&#39;s running speed without the user&#39;s direct operation.

TECHNICAL FIELD

The present invention relates to an automatic speed control apparatusfor a treadmill and a control method thereof, more particularly, to anautomatic speed control apparatus and control method thereof forautomatically controlling the proceeding speed of the track beltprecisely corresponding with a user's intention without the user'sdirect operation for changing the speed of the track belt while runningor walking on the treadmill.

BACKGROUND ART

A treadmill known as a running machine is widely used indoors such as athome or in a sports center as it allows users to have an effect ofexercising while working or running on its endlessly rotating belt innarrow space. Recently, a demand for treadmills is drasticallyincreasing due to the advantages of its safety and convenience becauseusers can exercise indoors using a treadmill even in the cold winter.

In general, a user on a treadmill runs or walks with directly changingthe speed of running or walking by finger operation so as to enjoydynamic exercise. In this regard, the user should directly operate thecontrol panel of the treadmill in order to control the proceeding speedof the track belt while running or walking on the belt. However, thefinger operation of the track belt speed while exercising on a treadmillcan be bothersome and even dangerous for the user on the movingtreadmill as it causes to break a balance of user.

Also, as a stereotyped program stored in a treadmill memory is notmanufactured without considering a user's body condition, the usershould follow the memorized stereotyped program regardless of user'scondition. Therefore, although the memorized program has a merit thatthe user does not need to directly operate the track belt speed duringthe exercise, the memorized program makes the user to exercise too muchor insufficiently

In order to overcome these problems, automatic speed control apparatusof running machine designed by Youngjin Chae, Korean patent No.2003-0069941 provides sensors 13, 14 comprised of a light emission partand a light receipt part on the front of control panel of the runningmachine which can sense where user is located. The apparatus accelerateswhen user is on the front of a track belt and on the contrarydecelerates when user is on the rear part of the track belt so that itcan automatically control the speed of track belt in accordance with theuser's intention. However, as the sensor used in the automatic speedcontrol apparatus of running machine designed by Youngjin Chae costs toomuch, the machine has a practical problem of losing pricecompetitiveness in manufacturing a running machine with the sensor.

On the other hand, as an automatic speed control apparatus of atreadmill using the sensor had not avoided high manufacturing cost,there has been an attempt to use an ultrasonic sensor for sensing thelocation of user. That is, an ultrasonic sensor located in a front partaccelerates a track belt rotation when the user gets closer to theultrasonic sensor and on the contrary it decelerates the track beltrotation when the user become more distant. However, the calculation ofthe distance of user from the sensor using an ultrasonic sensor is notprecise so that it causes malfunction which a treadmill accelerates abelt when the user does not get closer to the ultrasonic sensor ordecelerates even when the user is not distant from the ultrasonicsensor.

Moreover, a treadmill using a sensor for automatic speed control cancause serious malfunction as sensing simple gesture of running orwalking, or a movement for operating a controller located in a frontpart as an attempt to accelerate a belt. The speed of track belt canaccelerate when user does not want to run or walk faster.

DISCLOSURE OF INVENTION Technical Problem

These disadvantages of the prior art are overcome by the presentinvention. It is an object of the present invention to provide anautomatic speed control apparatus for a treadmill and control methodthereof automatically controlling the speed of track belt rotation touser's intention minutely without operating the treadmill specificallyfor changing the speed of rotation while running or walking on the trackbelt.

Another object of the present invention is to enable manufacturer toproduce an automatic speed control apparatus for a treadmillautomatically controlling the track belt with relatively low price.

Still another object of the present invention is to provide an automaticspeed control apparatus using a load sensor which senses that user'sspeed gets faster than the speed of track belt rotation when user issensed on the front part of the track belt, and therefore the treadmillaccelerates the belt. On the contrary, the load sensor senses thatuser's speed gets slower than the speed of track belt when user issensed on the rear part of the track belt, then the treadmilldecelerates the belt.

Yet another object of the present invention is to provide stable speedchange control device avoiding a drastic change of speed.

Still another object of the present invention is to provide comfortableexercise environment minimizing inertial force effect by the automaticspeed control of a track belt.

Another object of the present invention is to provide stable speedcontrol environment not to misperceive a movement of a user on a trackbelt for operating button on a control panel or grasping a hand purse asa sign to accelerate or decelerate the track belt.

Another object of the present invention is to provide a treadmill whichprevents possible accidents while exercising on a treadmill in advance.Another object of the present invention is to provide a treadmill ofreasonable price that can measure user's weigh on the treadmill.

Technical Solution

In order to attain the above mentioned object, the present inventionprovides a speed control apparatus for a treadmill including anendlessly rotating track belt, a driving unit for driving the track beltcomprising: at least one front load sensor located at the front part ofthe track belt for measuring a load from a user on the track belt; atleast one rear load sensor located at the rear part of the track beltfor measuring a load from the user on the track belt; and a control unitfor controlling the driving unit to accelerate or decelerate the speed(i.e., line velocity) of the track belt based on the measured values ofthe front load sensor and the rear load sensor.

That is, by sensing a running or walking user's location on the trackbelt from the measured loads at the front and the rear part of the trackbelt, the speed of the track belt can be automatically controlled inaccordance with the user's running or walking speed without specificallyoperating the treadmill for changing the speed of track belt during theuser's running or walking on the track belt.

Herein, the control unit controls the speed of the track belt toaccelerate when the user locates in the front part of the track belt,and to decelerate when the user locates in the rear part of the trackbelt by sensing the location and further the movement of the user fromthe difference(s) of the measured values of the front load sensor andthe rear load sensor.

The front load sensor is formed as at least one front load cell and therear load sensor is formed as at least one rear load cell. Generally, aload cell includes a or plural number of strain gages which is shrunkenor elongated by the external load. That is, as the resistance of thestrain gages is changed when an external load is applied, the voltage ofthe strain gage is also changed. From this voltage difference, thedeformation of the strain gage is calculated, accordingly, consideringthe material which the strain gage attaches, the load applied to thestrain gage can be measured. Therefore, in accordance with the degree ofthe user's biased location on the track belt, the front load sensor andthe rear load sensor formed as load cell output different voltages, andthus, the load can be measured by processing the voltage signals such asconverting the analog voltage signal into digital voltage signal.

For example, when the user is biasedly located at the front part of thetrack belt, the measured value of F1 at the front load sensor is gettingbigger comparing with the case when the user is located at the centerpart or at the rear part of the track belt. That is, from the changingpropensity of the measured value F1, the control unit can sense theuser's real time location on the track belt. Accordingly, in case thatthe absolute value of the measured value F1 at the front load sensor isgetting bigger, as the user is sensed to be located at the front part ofthe track belt, the control unit orders the driving unit to acceleratethe track belt. Similarly, when the user is biasedly located at the rearpart of the track belt, the measured value of F2 at the rear load sensoris getting bigger comparing with the case when the user is located atthe center part or at the front part of the track belt. Accordingly, incase that the absolute value of the measured value F2 at the rear loadsensor is getting bigger, as the user is sensed to be located at therear part of the track belt, the control unit orders the driving unit todecelerate the track belt.

To the contrary, the front load sensor and the rear load sensor can beformed as at least one strain gage. More specifically, the front loadsensor is formed as a pair of front strain gages installed at the frontpart of the track belt, and the rear load sensor is also formed as apair of rear strain gages installed at the rear part of the track belt,in which the front strain gages and the rear strain gages constitute afull wheatston bridge circuit. Instead, the front load sensor can beformed as a front strain gage installed at the front part of the trackbelt, and the rear load sensor can also be formed as a rear strain gageinstalled at the rear part of the track belt, in which the front straingage and the rear strain gage constitute a wheatston bridge circuit withother 2 dummy resistances.

In case that the load sensor is formed as a pair of strain gages, it isdesirable to install a pair of the front strain gages at both sides ofthe front part of the track belt and to install a pair of the rearstrain gages at both sides of the rear part of the track belt, wherebythe bias to the left side or to the right side can be automaticallycompensated. Also, as the resistance changes of 4 strain gages can berepresented by a bridge voltage, it is possible to precisely sense theuser's real time location with only one relatively expensive amplifier,thereby reducing the cost of the automatic speed control apparatus for atreadmill.

Herein, the front strain gages in the wheatston bridge circuit face eachother, and the rear strain gages therein also face each other. In thiscase, the bridge voltage ΔV can be expressed by following equation 1.

$\begin{matrix}{{\Delta \; V} = {V\frac{{R\; 1} - {R\; 2}}{{R\; 1} + {R\; 2}}}} & {{Equation}\mspace{20mu} 1}\end{matrix}$

Therefore, the resistance R1 of the front strain gage is getting biggerwhen the user is biasedly located at the front part of the track belt,while the resistance R2 of the rear strain gage is getting bigger whenthe user is biasedly located at the rear part of the track belt.Therefore, the sign and the absolute value of the bridge voltage ΔVsenses or catches the user's location (i.e., how much the user isbiasedly located on the track belt into the front part or into the rearpart) on real time. Based on the sensed the user's real time location,without requiring the user's operation of the control panel, theapparatus for automatically controlling the speed of the track belt inaccordance with the user's location on the track belt can be realized.Herein, it is effective that the resistances R1, R2 of all the straingages are all the same with one another, because the sign of bridgevoltage ΔV can be inverted whenever the user is biasedly located at thefront part or at the rear part of the track belt, thereby easily sensingthe user's location.

Also, when the user wishes to run faster on the track belt, the user isbiasedly located at the front part of the track bell Herein, as theabsolute value of the bridge voltage ΔV is changed in proportion to theuser's bias on the track belt, the control unit controls the degree ofacceleration or deceleration of the track belt in proportion to theabsolute value of the bridge voltage ΔV.

In order to prevent the track belt from being erroneously controlled dueto a so much sensitive control according to the user's location ormovement, it is preferable not to change the speed of the track beltwhen the user is located within a preset range in the center of thetrack belt, but to change the speed of the track belt only when the useris biasedly located out of the preset range and moves his or herlocation on the track belt.

Also, the front load sensor and the rear load sensor are installed atright and left sides respectively thereby easily sensing the user's biasto the front or the rear direction, although the user has a propensityto biasedly walk or run in the left side or the right side on the trackbelt.

Right after starting the exercise on the track belt, in order to sensethe user's propensity in terms of the location on the track belt, it ismore preferable to operate the track belt for predetermined time withoutchanging the speed of the track belt, to average the bridge voltage ΔVfor the predetermined time, and to store the average bridge voltage as areference bridge voltage ΔVref. This is to control the speed of thetrack belt considering the user's habitual preferred location on thetrack belt during the exercise. For example, when a user has apropensity to walk or run on the track belt a little bit front part onthe track belt, although the user is a little bit biasedly located infront part of the track belt during the exercise, as the user'spropensity is already reflected by the reference bridge voltage ΔVref,unless the user is more biasedly located to the front part of the trackbelt, the control unit does not control the track belt to accelerate.

The front load sensor(s) and the rear load sensor(s) are installed incontact with a frame which supports a deck located between the upper andthe lower faces of the track belt. Here, the deck also supports loads orimpacts from the user. That is, the front load sensor and the rear loadsensor can be installed respectively between the frame and the deck. Inaddition, the load can be measured by inferring the measured deflectionof the frame which supports the deck.

On the other hand, the present invention provides a speed control methodfor a treadmill including an endlessly rotating track belt, a drivingunit for driving the track belt comprising: a step of measuring loadsdue to the weight of a user on the track belt at least one front part ofthe track belt and at least one rear part of the track belt; a step ofaveraging the measured values at the front part of the track belt and atthe rear part of the track belt for preset time so as to recognize thelocation propensity of the user on the track belt; a step of sensing thelocation of the user on the track belt by comparing the measured valuesat front part of the track belt and at rear part of the track belt; anda step of controlling the speed of track belt to accelerate when theuser is sensed as being located at the front part of the track belt andto decelerate when the user is sensed as being located at the rear partof the track belt.

Similarly, the load in accordance with the user's location is measuredby a pair of front strain gages and a pair of rear strain gages havingthe same resistance with one another wherein the pair of the frontstrain gages and the pair of the rear strain gages constitute awheatston bridge in which the front strain gages face each other and therear strain gages face each other. Therefore, the control unit controlsthe speed of the track belt in accordance with the sign and the absolutevalue of the bridge voltage ΔV between the two points between the frontstrain gage and the rear strain gage.

On the other hand, the present invention provides a speed controlapparatus for a treadmill having a deck, a track belt of endlesslyrotating on the upper and the bottom face of the deck, and a drivingunit for driving the track belt comprising: at least one front loadsensor in the front part of the track belt and at least one rear sensorin the rear part of the track belt for sensing the location of a user onthe track belt; whereby the location of the user on the track belt issensed by comparing the measured values of the sensors, and the speed ofthe track belt is accelerated when the user move forward on the trackbelt and is decelerated when the user move backward on the track belt.

That is, based on the user's habit on the track belt that a user movesforward when the user wishes to run faster and that a user movesbackward when the user wishes to run slower, by comparing the measuredvalues from the load sensors with one another and sensing the user'sreal time location on the track belt, the speed of the track belt iscontrolled to be accelerated when the user moves forward and to bedecelerated when the user moves backward.

This control is to realize the speed control of the track belt inaccordance with the user's real time intention whether the user wishesto run faster or to run slower. Also, in case that a user wishes tochange the staying location on the track belt during the exercise, asthe speed of the track belt is not accelerated even though the user isbiasedly located at the front part of the track belt, this controlitself properly reflects the user's intention of only changing thestaying location thereon.

Herein, all said front load sensor and said rear load sensor are notlimited to means of independently measuring load, but includes asensor(s) to measure a load by combining the front load sensor with rearload sensor.

Also, the measured values from the front load sensor and the rear loadsensor are respectively averaged for a unit time, and then a differenceis calculated in accordance with time by subtracting the present averagevalue from the previous averaged one. In case that, after the absolutevalue of the difference maintains bigger than a preset criterion A, theabsolute value of the difference becomes smaller than the presetcriterion A, it is regarded that the user finishes forward or backwardmovement and stays within a predetermined range on the track belt. Atthis time, in case that the speed of the track belt is beingaccelerated, the speed of the track belt is decelerated for an instance,to the contrary, in case that the speed of the track belt is beingdecelerated, the speed of the track belt is accelerated for an instance.Herein, the preset criterion can be a preset value ΔFset based on themeasured load, or can be a preset value ΔVset based on the bridgevoltage in the wheatston bridge circuit, or can be preset value whichcan be converted therefrom. Further, the preset criterion can be presetbefore an exercise or during an exercise.

That is, at the moment that a user finishes movement on the track belt,as the user tends to continuously move in the previous direction due tothe inertia force, by instantly reverse acceleration or deceleration isapplied to the user, the user does not experience this unintended biascaused by the previous movement on the track belt.

The sensing of user's real time movement is realized by observing thedifference obtained by subtracting present averaged measured value for aunit time from the previous measured one. Concretely, for the unit timeΔt in which the movement of the user's center of gravity can be sensed,the measured values from the front and the rear load sensor arecontinuously averaged in real time in accordance with a shorter period(less than Δt), and the difference is calculated in real time bysubtracting the later average from the earlier averaged one, and thus,if the difference becomes bigger than the preset criterion A, it isnoticed that the user starts moving until the difference becomes smallerthan the preset criterion A.

On the other hand, in order to achieve the same object but not to causea possible impact to the user, in case that, after the absolute value ofthe difference maintains bigger than a preset criterion A, the absolutevalue of the difference becomes smaller than the preset criterion A, itis regarded that the user finishes forward or backward movement andstays within a predetermined range on the track belt, and thus, at thistime, in case that the speed of the track belt was being accelerated,the acceleration degree of the track belt is lowered for an instance, tothe contrary, in case that the speed of the track belt was beingdecelerated, the deceleration degree of the track belt is lowered for aninstance.

The present invention also provides a speed control apparatus fortreadmill including a deck, a track belt of endlessly rotating on theupper and the bottom face of the deck, and a driving unit for drivingthe track belt comprising: an accelerating area set at the front part onthe track belt for accelerating the speed of the track belt when a useris located at the accelerating area; a decelerating area set at the rearpart on the track belt for decelerating the speed of the track belt whenthe user is located at the decelerating area; and at least one frontload sensor located at the front part of the track belt and at least onerear load sensor located at the rear part of the track belt for sensingthe location of the user on the track belt, wherein the location of theuser is sensed by comparing the measured values from the front loadsensor and of the rear load sensor, and thus, the track belt isaccelerated when the user is on the accelerating area and the track beltis decelerated when the user is on the decelerating area.

Through setting the accelerating area and the decelerating area on thetrack belt by a manufacturer or a user, not by a user'sfinger-operation, the user can accelerate the track belt by moving ontothe accelerating area and can decelerate the track belt by moving ontothe decelerating area.

Herein, in order to provide a user with a stable constant speedenvironment, a constant speed area set at the middle part on the trackbelt for maintaining the speed of the track belt when the user islocated at the constant speed area is further comprised.

That is, in order to prevent the track belt from being erroneouslycontrolled due to a so much sensitive control, it is preferable not tochange the speed of the track belt when the user is located within apreset range in the middle of the track belt but to change the speed ofthe track belt only when the user is biasedly located out of the presetrange.

Also, it is also effective that the accelerating area and thedecelerating area are divided into plural areas respectively, andtherefore, if a user is located on the divided areas of the acceleratingarea, the degree of acceleration is differently set in accordance withthe divided areas. Similarly, if a user is located on the divided areasof the decelerating area, the degree of deceleration is differently setin accordance with the divided areas. Accordingly, as a user is morebiasedly located on the track belt, the user can make the speed of thetrack belt more promptly reach a targeted speed. Herein, the dividedarea is not limited to form an area by defining the area with a definiteboundary. Rather, the meaning of the divided area includes that theacceleration degree and the deceleration degree are continuouslyconverted in proportion to the degree of the user's bias although thedegree thereof is not converted in any boundary therebetween. Herein,the bias is expressed as the load difference ΔF or the bridge voltageΔV.

Generally, regardless of the user's location on the track belt,considering the user's intention on the track belt, if a user movesforward, the user is regarded as having an intention to accelerate theuser's running speed, similarly, if a user moves backward, the user issuspected as having an intention to decelerate the user's running speed.Therefore, although the user is not located on the accelerating area, itis desirable to accelerate the track belt when the user is sensed tomove forward on the track belt during the user's forward movement, andsimilarly to decelerate the track belt when the user is sensed to movebackward on the track belt during the user's backward movement.

Also, the measured value from the front load sensor and the rear loadsensor are respectively averaged for a unit time, and then a differenceis calculated in accordance with time by subtracting the present averagevalue from the previous averaged one. In case that, after the absolutevalue of the difference maintains bigger than a preset criterion A, theabsolute value of the difference becomes smaller than the presetcriterion A, it is regarded that the user finishes forward or backwardmovement and stays within a predetermined range on the track belt. Atthis time, in case that the speed of the track belt is beingaccelerated, the speed of the track belt is decelerated for an instance,to the contrary, in case that the speed of the track belt is beingdecelerated, the speed of the track belt is accelerated for an instance.

Thereafter, if the user stays on the accelerating area on the trackbelt, the speed of the track belt is accelerated, and if the user stayson the constant speed area on the track belt, the speed thereof ismaintained, and if the user stays on the decelerating area on the trackbelt, the speed thereof is decelerated.

Herein, when the user operates the control panel so that any signal isinput to the control panel, the speed and the inclination of the trackbelt is maintained for a pre-determined time with the condition at thetime when the signal was input. By being equipped with the abovefunction, although a user does not have any necessity to operate thecontrol panel during walking or running, in case that the user wishes tochange the exercise condition such as a running course or an inclinationof the track belt, the possibility to loss the user's balance can befundamentally prevented. As the predetermined time for maintaining itsexercise condition is enough for a user to operate the control panel,after the signal input via the control panel is terminated, the exercisecondition of the treadmill is maintained without being changed for 1 or2 seconds.

The acceleration or deceleration of the track belt is realized only whenthe differences of the measured values from the front and the rear loadsensors exceeds the preset criterion A, whereby the slight bias of theuser's location on the track belt may not cause the control foraccelerating or decelerating the track belt speed against the user'sintention.

Herein, the front load sensor and the rear load sensor are formed as aload cell respectively which can independently measure the load at itseach position thereby catching the user's location and movement from thedifference of the measured value. Here, so as to measure the load whichthe user applies to the deck, the front load sensor and the rear loadsensor are installed between the deck and the frame supporting the deck.

Herein, when the user on the track belt runs faster than the proceedingspeed of the track belt and thus is located at the front part thereof,the bridge voltage ΔV is also changed in proportion to the user's biason the track belt. Therefore, the control unit controls the speed of thetrack belt in accordance with the bridge voltage ΔV. Based on the changeof the average bridge voltage ΔVavg for a constant time Δt, the changeof the user's location between the present and the just before can becaught.

Also, the front load sensor and the rear load sensor are installed atthe left and at the right side respectively, thereby compensating theuser's propensity of biasedly located exercising in the left or theright direction and catching the user's location. Therefore, in case ofnot considering the reference bridge voltage ΔVref, whether the trackbelt is to be accelerated or be decelerated by the driving unit isdecided by the sign of the average bridge voltage ΔVavg, and the degreeof the acceleration and the deceleration is decided by the absolutevalue of the average bridge voltage ΔVavg.

In case of considering the reference bridge voltage ΔVref, whether thetrack belt is to be accelerated or be decelerated by the driving unit isdecided by the sign of the difference between average bridge voltageΔVavg and the reference bridge voltage ΔVref, and the degree of theacceleration and the deceleration is decided by the absolute value ofthe difference between average bridge voltage ΔVavg and the referencebridge voltage ΔVref.

As the front load sensor and the rear load sensor measure the load whichis transferred via the deck and thus are not revealed to the outside,the sensors can reliably and stably measure the load for a long time.

On the other hand, the present invention also provides a speed controlmethod for a treadmill including a deck, a track belt of endlesslyrotating on the upper and the bottom face of the deck, and a drivingunit for driving the track belt which comprises: a step of measuringloads ΔF, ΔV at points of at least one front part of the track belt andof at least one rear part of the track belt which are delivered via thedeck from the user; a step of catching the user's movement by comparingthe measured loads at points of at least one front part of the trackbelt and of at least one rear part of the track belt; a step ofcontrolling the track belt to accelerate while the user moves forward orto decelerate while the user moves backward.

Herein, a step of averaging the measured load for predetermined time atfront and rear part of the track belt from the user so as to catch theuser's location according to the user's propensity; a step of settingthe area to include the user's averaged location for the predeterminedtime as a constant speed area, of setting the area in front of theconstant speed area as an accelerating area, and of setting the area inrear of the constant speed area as a decelerating area are furthercomprised.

The step of catching the user's movement is realized by averaging themeasured load F1 or R1 at the front part and the measured load F2 or R2at the rear part for a unit time Δt, and by deciding whether the usermoves forward or moves backward when the sign of the difference betweenthe average value and the preset criterion i.e., A or ΔFset or ΔVsetbecomes bigger than the preset criterion.

After controlling the track belt to be accelerated or to be decelerated,an instant hesitant step of instantly reducing the degree ofaccelerating the track belt when the user finishes the forward movementand stays at on the track belt, or of instantly reducing the degree ofdecelerating the track belt when the user finishes the backward movementon the track belt, thereby preventing the user's bias due to the user'sinertia.

Thereafter, if the user stays on the accelerating area on the track beltthe speed of the track belt is accelerated, and if the user stays on theconstant speed area on the track belt the speed thereof is maintained,and if the user stays on the decelerating area on the track belt thespeed thereof is decelerated. Therefore, it is possible to prevent theuser from being biased due to the user's inertia and also tocontinuously control the proceeding speed of the track belt.

Herein, when the user operates the control panel and any signal is inputfrom the control panel, the exercise condition of the treadmill at thetime when the signal was input is maintained for a few seconds so as notto cause the user to lose the balance on the track belt.

Also, the present invention also includes a step of stopping the trackbelt when the user is sensed to be located at the too rear part of thetrack belt from the comparison of the measured value at the front partof the track belt with the measured value at the rear part thereof. Thisis to guarantee the safety of users by automatically stopping theproceeding operation of the track belt, when a novice at exercising onthe treadmill is too much biasedly pushed at the rear part of the trackbelt.

Also, the present invention provides a speed control method for atreadmill including a deck, a track belt of endlessly rotating on theupper and the bottom face of the deck, and a driving unit for drivingthe track belt which comprises: a step of measuring loads at points ofat least one front part of the track belt and of at least one rear partof the track belt which are delivered via the deck from the user; a stepof sensing the user's movement and/or user's location by comparing themeasured loads at points of at least one front part of the track beltand of at least one rear part of the track belt; a step of stopping thetrack belt when the change of the measured loads in accordance with timeis within the preset range.

That is, when there is not any change of load which is delivered via thedeck, as it is regarded that the user got off the treadmill withoutstopping the track belt, the track belt is obligatorily stopped therebypreventing a user from being damaged when the user unconsciously gets onthe treadmill.

Herein, whether there is any change of load from a user is sensed bywhether the change of the measured values from the load sensors exceedsthe preset value. As the preset value is set considering the measurementerror, the preset value is much smaller than the preset criterion A, orΔFset or ΔVset which is set for catching the user's movement.

On the other hand, the present invention provides a treadmill capable ofmeasuring the user's weight which comprises: a frame; a deck placed onthe frame; a track belt of endlessly rotating on the upper face and thebottom face of the deck; a wheatston bridge circuit including a pair offront strain gages installed on a front member between the frame and thedeck at the front part of the track belt and a pair of rear strain gagesinstalled on a rear member between the frame and the deck at the rearpart of the track belt wherein the front and the rear strain gages faceeach other respectively; a weighing place indicator for guiding the userto stand thereon which is separately located from the center of thefront strain gages and the rear strain gages;

and a weight indicator showing the user's weight from the wheatstonbridge circuit. Though the treadmill, without being equipped with aweighing device, when a user only gets on the weighing place on thetrack belt, the user can weigh the user's weight. The measuring methodof the user's weight can be obtained by the equation which express therelationship between the weighing place on the track belt and the bridgevoltage ΔV.

Meanwhile, the present invention also provides a speed control apparatusfor a treadmill including an endlessly rotating track belt, a drivingunit for driving the track belt comprising: a plurality of front loadsensors located at the front part of the track belt for measuring a loadfrom a user on the track belt; a plurality of rear load sensors locatedat the rear part of the track belt for measuring a load from the user onthe track belt; and a control unit for controlling the driving unit toaccelerate or decelerate the speed of the track belt based on themeasured values of the front load sensor and the rear load sensor.

By sensing the user's location from the measured values from the loadsensors and by controlling the driving unit to accelerate or deceleratethe proceeding speed of the track belt, the proceeding speed of thetrack belt can be automatically controlled in accordance with the user'srunning or walking speed, even though the user does not operate thecontrol panel during the exercise.

The control unit controls the driving unit to raise the degree ofacceleration as the value measured from the forefront load sensor ishigher, and similarly, the control unit controls the driving unit toraise the degree of deceleration as the value from the rearest loadsensors is higher. It is because the measured value of the forefrontload sensor is sensitively higher when a user is biasedly located at thefront part of the track belt, and also because the measured value of therearest load sensor is sensitively higher when a user is biasedlylocated at the rear part of the track belt.

The front load sensors and the rear load sensors can be at least oneload cell respectively. Also, the front load sensors and the rear loadsensors can be at least one pair of front strain gages and at least onepair of rear strain gages respectively, in which a pair of the frontstrain gages and a pair of the rear strain gages constitute a wheatstonbridge respectively.

In case that each of load sensors is formed as a pair of strain gages, afront strain gage of each of the front load sensors is installed at theright-front part of the track belt and the other front strain gage ofeach of the front sensors is installed at the left-front part of thetrack belt, and further, a rear strain gage of each of the rear loadsensors is installed at the right-rear part of the track belt and theother rear strain gage of each of the rear sensors is installed at theleft-rear part of the track belt, in which a pair of front strain gagesand the rear strain gages constitute a wheatston bridge respectively sothat the front strain gages may face each other in the wheatston bridgecircuit and the rear strain gages may face each other therein.Therefore, by observing the bridge voltage ΔV of each of the wheatonbridges, the user's location in addition to movement can be sensed.

With this construction with the resistance R1 of the front strain gageand the resistance R2 of the rear strain gage, the bridge voltage ΔV isexpressed as the above equation 1.

Accordingly, in case that the circuit has 3 wheatston bridges each ofwhich has a pair of front strain gages having resistances of R11, R12,R13 in order from the forefront one and a pair of rear strain gageshaving a resistance of Ro when the supplied voltage to the wheatstonbridge is V, each of the bridge voltage ΔV1, ΔV2, ΔV3 is expressed asfollowing equations. Herein, as the rear strain gages are exemplified asbeing formed at the same location, the resistances of 6 rear straingages are expressed as the same one Ro.

$\begin{matrix}{{\Delta \; V\; 1} = {V\; \frac{{Ro} - {R\; 11}}{{Ro} + {R\; 11}}}} & {{Equation}\mspace{20mu} 2} \\{{\Delta \; V\; 2} = {V\; \frac{{Ro} - {R\; 12}}{{Ro} + {R\; 12}}}} & {{Equation}\mspace{20mu} 3} \\{{\Delta \; V\; 3} = {V\; \frac{{Ro} - {R\; 13}}{{Ro} + {R\; 13}}}} & {{Equation}\mspace{20mu} 4}\end{matrix}$

Therefore, as the resistance R11 of the forefront one of the frontstrain gages becomes higher when the user is more biasedly located atthe front part of the track belt, and as the resistance R13 of therearest one of the front strain gages becomes higher when the user ismore biasedly located at the rear part of the track belt, the user'slocation and movement can be easily and precisely caught by the sign andthe absolute value of the bridge voltages ΔV1 to ΔV3. Through thisconstruction, even though a user does not directly operate the controlpanel generally in front of the track belt, the proceeding speed of thetrack belt can be automatically adjusted by controlling the drivingunit. Herein, as the sign of the bridge voltage ΔV is converted inaccordance with the user's location of the front part thereof or therear part thereof when the strain gages Ro, R11, R12, and R13 have thesame resistance value, it is desirable that the strain gages Ro, R11,R12, and R13 also have the same resistance value in view of the easinessof the speed control.

Also, in view that a user is more biased located at the front part ofthe track belt when a user runs faster than the proceeding speed of thetrack belt, and that the bridge voltage ΔV1 to ΔV3 is also changed inaccordance with the user's bias, the control unit controls the degree ofacceleration or deceleration in proportion to the absolute value of thebridge voltage ΔV1 to ΔV3.

In order to prevent the proceeding speed of the track belt from beingerroneously controlled due to a so much sensitive control according tothe user's location or movement, it is preferable not to change thespeed of the track belt when the user is located within a preset rangeof the center on the track belt but to change the speed of the trackbelt only when the user is biasedly located out of the preset range.

Also, in order to obtain the reliable control even when some of straingages are out of order, with excluding the maximum and minimum bridgevoltage from the bridge voltages ΔV1, ΔV2, ΔV3, . . . , the speed of thetrack belt can be controlled based on the sign and the absolute value ofthe rest of the bridge voltages.

Herein, as each of the bridge voltage ΔV1, ΔV2, ΔV3, . . . can bemeasured in real time, instead of controlling the speed of the trackbelt only based on the average bridge voltage ΔVavg, by controlling thespeed of the track belt based on ΔV1 or ΔV3 including the forefront oneof the front strain gages and the rearest one of the front strain gages,the proceeding speed of the track belt in accordance with the user'smovement can be promptly controlled. Therefore, compared with anapparatus having only a pair of front strain gages and a pair of rearstrain gages, the apparatus having plural pairs of front and rear straingages can control the proceeding speed of the track belt more preciselyand promptly with quick response time.

The front load sensors and the rear load sensors are installed incontact with the frame which supports the deck located between the upperand the lower faces of the track belt. Here, the deck also supportsloads or impacts from the user. That is, each of the front load sensorsand the rear load sensors can be installed between the frame and thedeck. In addition, the load can be measured by inferring from themeasured deflection of the frame which supports the deck considering thematerial property of the frame.

On the other hand, the present invention provides a A speed controlmethod for a treadmill including an endlessly rotating track belt, adriving unit for driving the track belt comprising: a step of measuringloads due to the weight of a user on the track belt at different pluralfront parts of the track belt and at one rear part of the track belt; astep of sensing the location of the user on the track belt by comparingthe measured values at front parts of the track belt and at the rearpart of the track belt; and a step of controlling the speed of trackbelt to be accelerated when the user is sensed as being located at afront part of the track belt and to be decelerated when the user issensed as being located at a rear part of the track belt.

At this time, by controlling the driving unit based on the averagemeasured value, even though any measurement error occurs at some of loadsensor(s), as the measurement error is compensated with the averagevalue, the proceeding speed can be controlled corresponding with theuser's intention.

ADVANTAGEOUS EFFECTS

As explained above, the present invention provides a speed controlapparatus for a treadmill including an endlessly rotating track belt, adriving unit for driving the track belt comprising at least one frontload sensor located in the front part of the track belt for measuring aweight of a user on the track belt, at least one rear load sensorlocated in the rear part of the track belt for measuring a weight of theuser on the track belt and a control unit for controlling the drivingunit to accelerate or decelerate the speed of the track belt based onthe measured values of the front load sensor and the rear load sensor.

Also, the front load sensor of the present invention is formed as atleast one front strain gage and the rear load sensor is formed as atleast one rear front strain gage so that an automatic speed controlapparatus for a treadmill of the present invention can acquire pricecompetitiveness.

The present invention can have more reliability as the malfunction dueto misperception of the simple gesture as a sign of acceleration ordeceleration has been removed by the mechanism to sense user's locationmeasuring a load point of the user on the track.

The present invention provides a stable speed change control deviceavoiding drastic change of speed.

The present invention also provides comfortable exercise environmentminimizing inertial force effect by the automatic speed control of atrack belt.

The present invention provides stable speed control environment not tomisperceive user's movement of user on a track belt for operating buttonon a control panel or grasping a hand purse as a sign to accelerate ordecelerate a belt.

BRIEF DESCRIPTION OF THE DRAWINGS

Accordingly, the present invention will be understood best throughconsideration of, and reference to, the following Figures, viewed inconjunction with the Detailed Description of the Preferred Embodimentreferring thereto, in which like reference numbers throughout thevarious Figures designate like structure and in which:

FIG. 1 is a diagram showing the structure of a treadmill in accordancewith a first embodiment.

FIG. 2 is a diagram illustrating the structure of a treadmill inaccordance with other embodiments.

FIG. 3 is a separate perspective view of a track part of FIG. 1 and FIG.2.

FIG. 4 is an expanded view illustrating part ‘A’ of FIG. 3.

FIG. 5 is a separated perspective view of a load sensor module of FIG.4.

FIG. 6 is a cross sectional view from the low side illustrating a trackpart without a track belt of FIG. 1 and FIG. 2.

FIG. 7 is an expanded view showing part ‘B’ of FIG. 6.

FIG. 8 is a circuit diagram using a load sensor of FIG. 1.

FIG. 9 is a diagram for the operation principle of FIG. 1.

FIG. 10 is a figure illustrating a sectioned accelerating area, aconstant speed area and a sectioned decelerating area on the track ofFIG. 2.

FIG. 11 is a diagram for a primary operation principle of FIG. 2.

FIG. 12 is a figure illustrating the change of speed in accordance withuser's movement from a constant speed area to an accelerating area andfrom the accelerating area to the constant speed area on the track belt.

FIG. 13 is a figure illustrating the change of speed in accordance withuser's movement from a constant speed area to a decelerating area andfrom the decelerating area to the constant speed area on the track belt.

FIG. 14 is a figure illustrating another change of speed in accordancewith user's movement from a constant speed area to an accelerating areaand from the accelerating area to the constant speed area on the trackbelt.

FIG. 15 is a figure illustrating another change of speed in accordancewith user's movement from a constant speed area to a decelerating areaand from the decelerating area to the constant speed area on the trackbelt.

FIG. 16 is a cross sectional view showing the composition of a treadmillin accordance with third embodiment of the present invention.

FIG. 17 is a separate perspective view illustrating a track part of FIG.16.

FIG. 18 is an expanded view of part ‘A’ of FIG. 17.

FIG. 19 is a perspective view from the low side illustrating a trackpart without a track belt of FIG. 16.

FIG. 20 is a figure showing a distribution of load sensors on a trackbelt of FIG. 15.

FIG. 21 is a separate perspective view of a front load sensor module ofFIG. 19.

FIG. 22 is an expanded view showing part ‘B’ with a rear load sensormodule of FIG. 19.

FIG. 23 is an expanded view showing part ‘C’ with a front load sensormodule of FIG. 19.

FIG. 24 is a control circuit using load sensors of FIG. 16.

FIG. 25 is a diagram illustrating operation principle of FIG. 16.

BEST MODE FOR CARRYING OUT THE INVENTION

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings. In describing the present invention, detaileddescription of laid-out function or structure is omitted in order toclarify the gist of the present invention.

As illustrated in FIG. 1 and FIGS. 3 to 9, a treadmill 100 equipped withan automatic speed control apparatus therefor of a first embodiment inaccordance with the present invention comprises a track unit 110 formaking the track belt 111 endlessly proceed so as to provide a user withexercise environment, a control panel unit 120 showing the operatingspeed and consumed calories in front of the track belt 111, load sensormodule 190 for measuring a load delivered from the user at the frontpart of the track belt 111 and at the rear part of the track belt 111,and control unit (not shown) for controlling the track belt to beaccelerated or decelerated based on the values measured by the loadsensor module 190.

The track unit 110 includes an endlessly rotating track belt 111 toprovide a user with a running or walking environment, a pair of rollers112 for guiding the track belt 111 at the end part thereof, a drivingunit 112 a for driving the rollers 112 so as to rotate the track belt111, a deck 113 formed as a plate located between the upper and lowerfaces of the track belt 111 so as to support weight or impact from theuser, a frame 114 in contact with both right and left end sides of thedeck 113 thereby supporting the deck 113, several cushion rubbers 115installed between the deck 113 and the frame 114 so as to absorbimpacts, a decoration cover 115 formed of metal material which coversboth sides of the frame 114 not to reveal the frame 114 to the outside,support rollers 117 for supporting the front part of the treadmill 100,support member 118 for supporting the rear part of the treadmill 100.

As illustrated in FIG. 3, the track belt 111 is installed to endlesslyrotate between the rollers 112, and the deck 113 is installed betweenthe upper and lower faces of the track belt 111. Herein, both end sidesof the deck 113 are placed on

shaped members 114 a protruded from the frame 114, and the cushionrubber 115 inserted between the deck member 114 a and the deck 113attenuates the impact load against the user's knees thereby protectingthe user's knees.

The control panel unit 120 includes a control panel 121 for indicatingthe present proceeding speed, a run distance, consumed calories etc. andhaving lots of input buttons for ordering the walking or running or forcontrolling the inclination of the track belt 111, a pair of handle rod122 protruded from the lower part of the control panel 121 for user'sgrasping during exercise or in emergency, connecting members 124extended from the track unit 110 so that the control panel 121 can belocated at the height of the user's waist, a parallel member connectingboth of the connecting members 124 for reinforcing the transversestiffness of the connecting members 124.

The load sensor module 190 is respectively installed at the front partand at the rear part of the track belt 111 so as to measure loadsdelivered via the deck 113 from the user. The load sensor module 190includes medium members 191 transversely protruded from the frame 114,bending members 192 fixed to each of the medium members 191 for beingappropriately bent by the load via the deck 113, strain gages 193 a, 193b, 194 a, and 194 b attached on each of the bottom faces of the bendingmembers 192, whereby the strain gages are deformed in accordance withthe deformation of the bending members 192 within the elastic rangethereof.

Herein, the medium member 191 and the bending member 192 are firmlycombined by fastening means such as bolt's penetrating of the holes 191a, 192 a when the members 191, 192 are folded, whereby the members 191,192 are to be integrally deformed together with each other. The otherhole 192 b of the bending member 192 which is aligned with a hole of thecushion rubber 115 is used to combine the bending member 192 with thecushion rubber 115.

As illustrated in FIG. 8, the control unit includes a wheatston bridgewhich includes a pair of front strain gages 194 a, 194 b havingresistance R2 for measuring load at the front part of the track belt 111and a pair of rear strain gages 193 a, 193 b having resistance R1 formeasuring load at the rear part of the track belt 111 wherein the pairof the front strain gages 194 a, 194 b face each other and the pair ofthe rear strain gages 193 a, 193 b face each other. Also, the controlunit includes an amplifier for amplifying the bride voltage ΔV between afirst point 181 and a second point 182 which is placed between the frontstrain gages 194 a,194 b and the rear strain gages 193 a, 193 b, ananalog-digital converter for converting the amplified analog bridgevoltage into digitalized bridge voltage for signal processing. That is,the control unit controls the driving unit 112 a to accelerate or todecelerate the rotation of the rollers 112 thereby controlling theproceeding speed of the track belt 111.

At this time, when voltage V is applied to the wheatston bridge circuit,the bridge voltage ΔV between a first point 181 and a second point 182is expressed as the fore-mentioned equation 1.

Therefore, when a user is biasedly located at the front part or the rearpart of the track belt 111, the resistance of the strain gage installedat which the user is biasedly located is greater than one at which theuser is not biasedly located. Therefore, the sign of bridge voltage ΔVis converted by whether the user is biasedly located at the front partor at the rear part of the track belt 111. Further, as the user is morebiasedly located at any part of the track belt 111, the amount (i.e.,absolute value) of the bridge voltage ΔV becomes greater, therefore, thedegree of acceleration or deceleration is determined in proportion tothe amount of the bridge voltage ΔV.

Herein, the front strain gages 194 a, 194 b and the rear strain gages193 a, 193 b are formed as having the same resistance. However, anyvalue of resistance such as 120Ω or 350Ω is acceptable.

Below, referring to FIG. 9, the operation principle of the automaticspeed control apparatus of the first embodiment in accordance with thepresent invention is to be explained.

Firstly, the allowable range of a user's bias not to change theproceeding speed of the track belt is stored and preset in a form of theconverted bridge voltage ΔVset (i.e., initial preset voltage) in thecontrol unit.

Thereafter, when a user gets on the treadmill and pushes a start buttonon the control panel 121 to walk or run on the track belt, withoutautomatically changing the speed of the track belt 111 for about 1minutes, the load sensor module 190 measures the loads via the deck 113from the user both at the front part of the track belt 111 and at therear part of the track belt 111, whereby the user's propensity onwhether the user likes to exercise at a little bit front part or rearpart of the track belt 111 can be grasped. Concretely, for about oneminute right after starting an exercise, average voltage of the measuredbridge voltage ΔV of the wheatston bridge illustrated in FIG. 8 isstored as a reference bridge voltage ΔVref which is a criterion whetherto change the proceeding speed of the track belt 111 or not.

Thereafter, when the user runs faster and becomes biasedly located atthe front part of the track belt 111, as the bending member 192 at thefront part thereof is deflected more than one at the rear part thereof,the resistance R2 of the front strain gages 194 a, 194 b becomesgreater, however, the resistance R1 of the rear strain gages 193 a, 193b is little changed because the bending member 192 at the rear partthereof is little bent. Therefore, according to the equation 1, the signof the bridge voltage ΔV becomes minus (−), and the absolute value ofthe bridge voltage ΔV becomes greater as the user is more biasedlylocated on the track belt 111. At this time, when the absolute value ofΔV−ΔVref exceeds the initial preset voltage ΔVset, as the degree of theuser's front bias exceeds the initial preset degree, even though anysignal to accelerate is not input from the user, the control unitcontrols the proceeding speed of the track belt 111 to be accelerated inproportion to the absolute value of ΔV−ΔVref.

Similarly, when the user runs slower and becomes biasedly located atreart part of the track belt 111, as the bending member 192 at the rearpart thereof is deflected more than one at the front part thereof, theresistance R1 of the rear strain gages 193 a, 193 b becomes greater,however, the resistance R2 of the front strain gages 194 a, 194 b islittle changed because the bending member 192 at the rear part thereofis little bent. Therefore, according to the equation 1, the sign of thebridge voltage ΔV becomes plus (+), and the absolute value of the bridgevoltage ΔV becomes greater as the user is more biasedly located on thetrack belt 111. At this time, when the absolute value of ΔV−ΔVrefexceeds the initial preset voltage ΔVset, as the degree of the user'srear bias exceeds the initial preset degree, even though any signal todecelerate is not input from the user, the control unit controls theproceeding speed of the track belt 111 to be decelerated in proportionto the absolute value of ΔV−ΔVref.

Herein, whether to accelerate or to decelerate the proceeding speed ofthe track belt is determined by the sign of ΔV−ΔVref.

The automatic speed control continues until the user stops the exercise.

MODE FOR THE INVENTION

Hereinafter, a second embodiment of the present invention is to beexplained.

As illustrated in FIGS. 2 to 8 and FIGS. 10 to 15, a treadmill 100equipped with an automatic speed control apparatus therefor of a secondembodiment in accordance with the present invention comprises a trackunit 110 for making the track belt 111 endlessly proceed so as toprovide a user with exercise environment, control panel unit 120 showingthe operation speed and consumed calories in front of the track belt111, load sensor module 190 for measuring load delivered from the userat the front part of the track belt 111 and at the rear part of thetrack belt 111, and a control unit (not shown) for controlling the trackbelt to be accelerated or decelerated based on the values measured bythe load sensor module 190.

The track unit 110 includes an endlessly rotating track belt 111 toprovide a user with a running or walking environment, a pair of rollers112 for guiding the track belt 111 at the end part thereof, a drivingunit 112 a for driving the rollers 112 so as to rotate track belt 111, adeck 113 formed as a plate located between the upper and the lower facesof the track belt 111 so as to support weight or impact from the user, aframe 114 in contact with both right and left end sides of the deck 113thereby supporting the deck 113, several cushion rubbers 115 installedbetween the deck 113 and the frame 114 so as to absorb impacts, adecoration cover 115 formed of metal material which covers both sides ofthe frame 114 not to reveal the frame 114 to the outside, supportrollers 117 for supporting the front part of the treadmill 100, supportmember 118 for supporting the rear part of the treadmill 100.

As illustrated in FIG. 3, the track belt 111 is installed to endlesslyrotate between the rollers 112, and the deck 113 is installed betweenthe upper and lower faces of the track belt 111. Herein, both end sidesof the deck 113 are placed on

shaped members 114 a protruded from the frame 114, and the cushionrubber 115 inserted between the deck member 114 a and the deck 113attenuates the impact load reacted to the user's knees therebyprotecting the user's knees.

Herein, an accelerating area 151, I is formed at the front part of thetrack belt 111, and a constant speed area 152, II is formed at themiddle part of the track belt 111, and a decelerating area 153, III isformed at the rear part of the track belt 111. That is, when a user islocated at the accelerating area 151, I, the proceeding speed of thetrack belt is accelerated, and when a user is located at the constantspeed area 152, II, the proceeding speed of the track belt ismaintained, and when a user is located at the decelerating area 153,III, the proceeding speed of the track belt is decelerated.

As shown in FIG. 10, the accelerating area 151 is divided into a firstaccelerating area 151 a located at the forefront part of theaccelerating area 151, a second accelerating area 151 b located at themiddle part of the accelerating area 151, and a third accelerating area151 c located at the rearest part of the accelerating area 151.Therefore, when a user is located at the first accelerating area 151 a,the speed of the track belt 111 is accelerated at the highest degree ofacceleration. To the contrary, when a user is located at the thirdaccelerating area 151 c, the speed of the track belt 111 is acceleratedat the lowest degree of acceleration.

Also, the decelerating area 153 located at just rear part of theconstant speed area 152 is divided into a first decelerating area 153 alocated at the forefront part of the decelerating area 153, a seconddecelerating area 153 b located at the middle part of the deceleratingarea 153, and a stop area 153 c located at the rearest part of thedecelerating area 153. Herein, when a user is located at the seconddecelerating area 153 b, the speed of the track belt 111 is morepromptly decelerated compared with when a user is located at the firstdecelerating area 153 a. Also, when a user is located at the stop area,as it is regarded that the user is pushed into the rearest part of thetrack belt 111 due to an immature skill or being too exhausted, in orderto guarantee the user's safety, the proceeding of the track belt isslowly stopped.

The control panel unit 120 includes a control panel 121 for indicatingthe present proceeding speed, a run distance, consumed calories etc. andhaving lots of input buttons for ordering the walking or running or forcontrolling the inclination of the track belt 111, a pair of handle rods122 protruded from the lower part of the control panel 121 for user'sgrasping during exercise or in emergency, connecting members 124extended from the track unit 110 so that the control panel 121 belocated at the height of the user's waist, a parallel member connectingboth of the connecting members 124 for reinforcing the transversestiffness of the connecting members 124.

Herein, an hand pulse for measuring a user's pulse is installed on thesurface of the connecting member 124.

The load sensor module 190 is respectively installed at the front partand at the rear part of the track belt 111 so as to measure loadsdelivered via the deck 113 from the user. The load sensor module 190includes medium members 191 transversely protruded from the frame 114,bending members 192 fixed to each of the medium members 191 for beingappropriately bent by the load via the deck 113, strain gages 193 a, 193b, 194 a, and 194 b attached on each of the bottom faces of the bendingmembers 192, whereby the strain gages are deformed in accordance withthe deformation of the bending members 192 within the elastic rangethereof.

Herein, the medium member 191 and the bending member 192 are firmlycombined by fastening means such as bolt's penetrating of the holes 191a, 192 a when the members 191, 192 are folded, whereby the members 191,192 are to be integrally deformed together with each other. Other holes192 b of the bending member 192 which is aligned with a hole of thecushion rubber 115 is used to combine the bending member 192 with thecushion rubber 115.

As illustrated in FIG. 8, the control unit includes a wheatston bridgewhich a pair of front strain gages 194 a, 194 b having resistance R2 formeasuring load at the front part of the track belt 111 and a pair ofrear strain gages 193 a, 193 b having resistance R1 for measuring loadat the rear part of the track belt 111 wherein the pair of the frontstrain gages 194 a, 194 b face each other and the pair of the rearstrain gages 193 a, 193 b face each other. Also, the control unitincludes an amplifier for amplifying the bride voltage ΔV between afirst point 181 and a second point 182 which is placed between the frontstrain gages 194 a,194 b and the rear strain gages 193 a, 193 b, ananalog-digital converter for converting the amplified analog bridgevoltage into digital bridge voltage for signal processing. That is, thecontrol unit controls the driving unit 112 a to accelerate or todecelerate the rotation of the rollers 112 thereby controlling theproceeding speed of the track belt 111.

At this time, when voltage V is applied to the wheatston bridge circuit,the bridge voltage ΔV between a first point 181 and a second point 182is expressed as the fore-mentioned equation 1.

Therefore, when a user is biasedly located at the front part or the rearpart of the track belt 111, the resistance of the strain gage installedat which the user is biasedly located is greater than one at which theuser is not biasedly located. Therefore, the sign of bridge voltage ΔVis converted by whether the user is biasedly located at the front partor at the rear part of the track belt 111. Further, as the user is morebiasedly located at any part of the track belt 111, the amount (i.e.,absolute value) of the bridge voltage ΔV becomes greater, therefore, thedegree of acceleration or deceleration is determined in proportion tothe amount of the bridge voltage ΔV.

Here, as the analog bridge voltage ΔV forms a sine wave, an error canoccurs according to the measurement time. Therefore, it is necessary toaverage the bridge voltage ΔV for a unit time Δt for which the movementof a user's center of gravity can be sensed. Accordingly, the speedcontrol apparatus of the present embodiment catches a user's movementbased on the average bridge voltage ΔVavg for the unit time Δt.

Moreover, the front strain gages 194 a, 194 b and the rear strain gages193 a, 193 b are formed as having the same resistance. However, anyvalue of resistance such as 120Ω or 350Ω is acceptable.

Below, referring to FIG. 11, the operation principle of the automaticspeed control apparatus of the second embodiment in accordance with thepresent invention is to be explained.

Firstly, the allowable range of a user's bias not to change theproceeding speed of the track belt is stored and preset in a form of theconverted bridge voltage ΔVset (i.e., initial preset voltage) in thecontrol unit.

Thereafter, when a user gets on the treadmill and pushes a start buttonon the control panel 121 to walk or run on the track belt, withoutautomatically changing the speed of the track belt 111 for about 15seconds, the load sensor module 190 measures the loads via the deck 113from the user both at front part of the track belt 111 and at the rearpart of the track belt 111, whereby the user's propensity on whether theuser likes to exercise at a little bit front part or rear part of thetrack belt 111 can be grasped. Concretely, for about one minute rightafter starting an exercise, an average voltage of the measured bridgevoltage ΔV of the wheatston bridge illustrated in FIG. 8 is stored as areference bridge voltage ΔVref which is a criterion whether to changethe proceeding speed of the track belt 111 or not.

Thereafter, in case that the user runs faster than the proceeding speedof the track belt 111 and thus the user is biasedly located at the frontpart of the track belt 111, the average bridge voltage ΔVavg for a unittime Δt, for which the movement of a user's center of gravity can besensed, is continually or periodically obtained.

Thus, as the user moves forward or backward on the track belt, theaverage bridge voltage ΔVavg is continuously changed, and also, thedifference ΔVavg−ΔVref between the average bridge voltage ΔVavg and thereference bridge voltage ΔVref is also changed. At this time, ascontrolling the speed of the track belt 111 only based on the differenceΔVavg−ΔVref may cause the unstable exercise environment, it is desirableto control the speed of the track belt 111 to be changed only when thedifference ΔVavg−ΔVref exceeds the preset criterion A or AFset or ΔVset.That is, whether the track belt to be accelerated or to be deceleratedis determined by the sign of the difference ΔVavg−ΔVref, and the degreeof the acceleration or deceleration is determined by the absolute valueof the difference ΔVavg−ΔVref.

Accordingly, when the absolute value of the difference ΔVavg−ΔVrefexceeds the initial preset criterion ΔVset, it is regarded that the useris moving on the track belt 111. Thus, if the user is moving forward,the track belt is controlled to be accelerated, and if the user ismoving backward, the track belt is controlled to be decelerated.

When a user moves forward over the initially preset range, as thebending member 192 at the front part thereof is deflected more than oneat the rear part thereof, the resistance R2 of the front strain gages194 a, 194 b becomes greater, however, the resistance R1 of the rearstrain gages 193 a, 193 b is little changed because the bending member192 at the rear part thereof is little bent. Therefore, according to theequation 1, the sign of the bridge voltage ΔVavg becomes minus (−), andthe absolute value of the bridge voltage ΔVavg becomes greater as theuser is more biasedly located on the track belt 111. At this time, asthe absolute value of ΔVavg−ΔVref exceeds the initial preset voltageΔVset, even though any signal to accelerate is not input from the user,the control unit controls the proceeding speed of the track belt 111 tobe accelerated in proportion to the absolute value of ΔVavg−ΔVref.

Similarly, when a user moves forward over the initially preset range, asthe bending member 192 at the rear part thereof is deflected more thanone at the front part thereof, the resistance R1 of the rear straingages 193 a, 193 b becomes greater, however, the resistance R2 of thefront strain gages 194 a, 194 b is little changed because the bendingmember 192 at the rear part thereof is little bent. Therefore, accordingto the equation 1, the sign of the bridge voltage ΔV becomes plus (+),and the absolute value of the bridge voltage ΔVavg becomes greater asthe user is more biasedly located on the track belt 111. At this time,as the absolute value of ΔVavg−ΔVref exceeded the initial preset voltageΔVset, even though any signal to decelerate is not input from the user,the control unit controls the proceeding speed of the track belt 111 tobe decelerated in proportion to the absolute value of ΔVavg−ΔVref.

To the contrary, when the absolute value of the difference ΔVavg−ΔVrefis smaller than the initially preset criterion ΔVset, it is sensed thatthe user does not move on the track belt. In this case, when the user islocated on the accelerating area 151, the track belt 111 is controlledto be accelerated, and when the user is located on the constant speedarea 152, the track belt 111 is controlled to be maintained with aconstant speed, and when the user is located on the decelerating area153, the track belt 111 is controlled to be decelerated.

At this time, which area the user is located at can be sensed by thedifference ΔVavg−ΔVref.

Herein, when a user moves from the constant speed area 152 to theaccelerating area 151 or from the accelerating area 151 to thedecelerating area 153, as the direction of the user's movement coincideswith the direction of the velocity vector of the track belt, the usertends to be biased due to the inertia against the user's intention.Further, considering that the inertia is maximized when a user stops hisor her movement, it is effective to instantly apply an acceleration ordeceleration pattern which is opposite to the user's movement at thetime when the user finishes a forward or backward movement (i.e., whenthe absolute value of the difference ΔVavg−ΔVref exceeds the initiallypreset criterion ΔVset) thereby preventing the user's being biasedagainst the user's intention.

When a user moves forward so as to directly operate the control panel121, the user is generally located at the front part of the track belt111. In this case, as the user did not intend to run faster,accelerating the track belt makes the user feel uncomfortable.Therefore, in case that any signal is input from the control panel 121,the operation condition such as the proceeding speed and the inclinationof the track belt 111 is constantly maintained for the time being.

Also, in case that a user is pushed to be located at the rearest part ofthe track belt 111, in order to guarantee the user's safety, the controlunit 120 stops the operation of the driving unit 112 a.

The automatic speed control continues until the user stops the exercise.

Below, referring to FIGS. 12 and 13, a first operation example inaccordance with the automatic speed control apparatus for a treadmill isto be explained. The first operation example is to remove the use'sunintentional bias by applying the acceleration or deceleration patternwhich is opposite to the user's movement direction at the time when theuser finishes his or her movement.

FIG. 12 shows a diagram 201 of the user's location in accordance withtime (the right longitudinal axis) and a diagram 301 of the speed of thetrack belt in accordance with time when a user moves from a constantspeed area to an accelerating area and then from the accelerating areato the constant speed area on the track belt 111.

As long as a user stays at the constant speed area 152 (˜t1), the trackbelt is also controlled to run at a constant speed. In case that theuser starts to move from the constant speed area 152 to the accelerationarea 151 (t1˜t2), as it is regarded that the user wishes to run faster,although the user stays in the constant speed area 152, the track beltis controlled to be accelerated during the user's forward movement.Thereafter, when the user crosses into the accelerating area 151(t2˜t3), the track belt 111 is controlled to be accelerated with thehigher degree of acceleration.

In case that the user starts to stay at the accelerating area 151(t3˜t4), in order to prevent the user from being biased due to theinertia force against the user's intention, the track belt 111 iscontrolled to be instantly decelerated. Thereafter, as the user islocated at the accelerating area 151, the track belt is controlled to beaccelerated with the predetermined acceleration in accordance with theaccelerating area 151 a, 151 b, and 151 c.

When the user starts to move backward from the accelerating area 151(t4˜t5), as the user intends to run slower, although the user is locatedwithin the accelerating area 151, the track belt 111 is controlled to bedecelerated with the low degree of deceleration. Also, even when theuser reaches the constant speed area 152 (t5˜t6), the track belt 111 iscontrolled to be gently decelerated. At the time when the user finishesthe backward movement and stays at the constant speed area 152, in orderto prevent the user to be biased due to the inertia force against theuser's intention, the track belt 111 is controlled to be instantlyaccelerated, and then, to be maintained at a constantspeed.

Herein, the instant deceleration at t3 and the instant acceleration att6 are determined respectively by the degree of the acceleration justbefore t3 and the degree of deceleration just before t6, therebyeffectively preventing the user's unintentional bias due to the inertiaforce.

FIG. 13 shows a diagram 202 of the user's location in accordance withtime (right longitudinal axis) and a diagram 302 of the speed of thetrack belt in accordance with time when a user moves from a constantspeed area to a decelerating area and then from the decelerating area tothe constant speed area on the track belt 111.

As long as a user stays at the constant speed area 152 (˜t1), the trackbelt is also controlled to run at a constantspeed. In case that the userstarts to move from the constant speed area 152 to the deceleration area153 (t1˜t2), as it is regarded that the user wishes to run slower,although the user stays in the constant speed area 152, the track beltis controlled to be gently decelerated during the user's backwardmovement. Thereafter, when the user crosses into the decelerating area153 (t2˜t3), the track belt 111 is controlled to be decelerated with thehigher degree of deceleration.

In case that the user starts to stay at the decelerating area 153(t3˜t4), in order to prevent the user from being biased due to theinertia force against the user's intention, the track belt 111 iscontrolled to be instantly accelerated. Thereafter, as the user islocated at the decelerating area 153, the track belt is controlled to bedecelerated with the predetermined acceleration in accordance with thedecelerating area 153 a, 153 b. Herein, if the user is located at therearest part of the track belt 111, i.e., a stop area 153 c, the trackbelt 111 is controlled to be stopped.

When the user starts to move forward from the decelerating area 153(t4˜t5), as the user intends to run faster, although the user is locatedwithin the decelerating area 153, the track belt 111 is controlled to begently accelerated. Also, even when the user reaches the constant speedarea 152 (t5˜t6), the track belt 111 is still controlled to be gentlyaccelerated. At the time when the user finishes the forward movement andstays at the constant speed area 152, in order to prevent the user to bebiased due to the inertia force against the user's intention, the trackbelt 111 is controlled to be instantly decelerated, and then, to bemaintained at a constantspeed.

Herein, the instant acceleration at t3 and the instant deceleration att6 are determined respectively by the degree of the deceleration justbefore t3 and the degree of acceleration just before t6, therebyeffectively preventing the user's unintentional bias due to the inertiaforce.

Below, referring to FIGS. 14 and 15, a second operation example inaccordance with the automatic speed control apparatus for a treadmill isto be explained. The second operation example is also to remove theuse's unintentional bias by applying the lowered acceleration or lowereddeceleration pattern which is the same with the user's movementdirection at the time when the user finishes his or her movement.

FIG. 14 shows a diagram 201 of the user's location in accordance withtime (right longitudinal axis) and a diagram 401 of the speed of thetrack belt in accordance with time when a user moves from a constantspeed area to an accelerating area and then from the accelerating areato the constant speed area on the track belt 111.

The control pattern of the second operation example from t1 to t3 is thesame to the above-described first operation example referring to FIG.12. However, the second operation example has an object to reduce thedegree of impact which the user may feel uncomfortable at the time whenthe opposite pattern of acceleration or deceleration is instantlyapplied. Therefore, instead of applying the opposite pattern ofacceleration or deceleration to the user's movement, the secondoperation example applies the alleviated acceleration or decelerationcorresponding to the user's movement. Concretely, when the user startsto move backward from the accelerating area 151 (t4˜t5), as long as theuser is located within the accelerating area 151, the track belt 111 iscontrolled to be accelerated with the lower degree of acceleration.Further, when the user reaches the constant speed area 152 (t5˜t6), thetrack belt 111 is controlled to be accelerated with the much lowerdegree of acceleration than that during t4˜t5. Further, when the userstays at the constant speed area 153 (t6˜), in order to prevent the userfrom being influenced by backward inertia force, the track belt 111 iscontrolled to be instantly accelerated. Herein, the degree ofacceleration is lower than that at t6 of FIG. 12. Thereafter, as theuser is located at the constant speed area, the track belt 111 iscontrolled to be uniformly maintained.

FIG. 15 shows a diagram 202 of the user's location in accordance withtime (right longitudinal axis) and a diagram 402 of the speed of thetrack belt in accordance with time when a user moves from a constantspeed area to a decelerating area and then from the decelerating area tothe constant speed area on the track belt 111.

Similarly, the control pattern of the second operation example from t1to t3 is the same to the above-described first operation examplereferring to FIG. 13. However, the second operation example has anobject to reduce the degree of impact which the user may feeluncomfortable at the time when the opposite pattern of acceleration ordeceleration is instantly applied. Therefore, instead of applying theopposite pattern of acceleration or deceleration to the user's movement,the second operation example applies the alleviated acceleration ordeceleration corresponding to the user's movement. Concretely, when theuser starts to move forward from the decelerating area 153 (t4˜t5), aslong as the user is located within the decelerating area 153, the trackbelt 111 is controlled to be decelerated with the lower degree ofdeceleration. Further, when the user reaches the constant speed area 152(t5˜t6), the track belt 111 is controlled to be decelerated with themuch lower degree of deceleration than that during t4˜t5. Further, whenthe user stays at the constant speed area 153 (t6˜), in order to preventthe user from being influenced by forward inertia force, the track belt111 is controlled to be instantly decelerated. Herein, the degree ofdeceleration is lower than that at t6 of FIG. 14. Thereafter, as theuser is located at the constant speed area, the track belt 111 iscontrolled to be uniformly maintained.

The automatic speed control continues until the user stops the exercise

Hereinafter, a third embodiment of the present invention is to beexplained.

As illustrated in FIGS. 16 to 25, a treadmill 100 equipped with anautomatic speed control apparatus therefor of a first embodiment inaccordance with the present invention comprises a track unit 110 formaking the track belt 111 endlessly proceed so as to provide a user withexercise environment, control panel unit 120 showing the operating speedand consumed calories in front of the track belt 111, a load sensormodule 190 for measuring load delivered from the user at the front partof the track belt 111 and at the rear part of the track belt 111, and acontrol unit (not shown) for controlling the track belt to beaccelerated or decelerated based on the values measured by the loadsensor module 190.

The track unit 110 includes an endlessly rotating track belt 111 toprovide a user with a running or walking environment, a pair of rollers112 for guiding the track belt 111 at the end part thereof, a drivingunit 112 a for driving the rollers 112 so as to rotate track belt 111, adeck 113 formed as a plate located between the upper and lower faces ofthe track belt 111 so as to support weight or impact from the user, aframe 114 in contact with both right and left end sides of the deck 113thereby supporting the deck 113, several cushion rubbers 115 installedbetween the deck 113 and the frame 114 so as to absorb impacts, adecoration cover 115 formed of metal material which covers both sides ofthe frame 114 not to reveal the frame 114 to the outside, supportrollers 117 for supporting the front part of the treadmill 100, supportmember 118 for supporting the rear part of the treadmill 100.

As illustrated in FIG. 17, the track belt 111 is installed to endlesslyrotate between the rollers 112, and the deck 113 is installed betweenthe upper and lower faces of the track belt 111. Herein, both end sidesof the deck 113 are placed on

shaped members 114 a protruded from the frame 114, and the cushionrubber 115 inserted between the deck member 114 a and the deck 113attenuates the impact load against the user's knees thereby protectingthe user's knees.

The control panel unit 120 includes a control panel 121 for indicatingthe present proceeding speed, a run distance, consumed calories etc. andhaving lots of input buttons for ordering the walking or running or forcontrolling the inclination of the track belt 111, a pair of handle rod122 protruded from the lower part of the control panel 121 for user'sgrasping during exercise or in emergency, connecting members 124extended from the track unit 110 so that the control panel 121 belocated at the height of the user's waist, a parallel member connectingboth of the connecting members 124 for reinforcing the transversestiffness of the connecting members 124. However, the proceeding speedof the track belt is automatically controlled corresponding with theuser's intention, a button for controlling the speed of the track belt111 is not formed on the control panel 121.

The load sensor module 190 is respectively installed at the front partand at the rear part of the track belt 111 so as to measure loadsdelivered via the deck 113 from the user. The load sensor module 190includes medium members 191 transversely protruded from the frame 114,bending members 192 fixed to each of the medium members 191 for beingappropriately bent by the load via the deck 113, strain gages 171 a-173b, 181 a-183 b attached on each of the bottom faces of the bendingmembers 192, whereby the strain gages are deformed in accordance withthe deformation of the bending members 192 within the elastic rangethereof.

Herein, 6 front strain gage modules having a strain gage 181 a, 182a,183 a, 181 b,181 b,183 b respectively are installed at the front partof the deck 113.

Specifically, 6 front strain gage modules are divided into 3 pairs offront strain gage modules (i.e., 181 a-181 b, 182 a-182 b, 183 a-183 b),and as illustrated in FIG. 20, each pair of front strain gage modulesare installed at the right side and at the left side of different frontparts of the track belt 111. On the contrary, 2 rear strain gage moduleshaving 3 strain gages 171 a-173 a, 171 b-173 b respectively areinstalled at the rear part of the deck 113. Specifically, as illustratedin FIG. 20, 2 rear strain gage modules (i.e., 171 a-173 a, 171 b-173 b)are respectively installed at the right side and at the left side of thesame rear part of the track belt 111. That is, each party including 3rear strain gagaes 171 a-173 a or 171 b-173 b are attached parallel withone another on a bending member 192 and thus 3 rear strain gages 171a-173 a or 171 b-173 b in a party are equally deflected and thus havethe equal change of their resistances.

Also, the medium member 191 and the bending member 192 are firmlycombined by fastening means such as bolt's penetrating of the holes 191a, 192 a when the members 191, 192 are folded, whereby the members 191,192 are to be integrally deformed together with each other. Other hole192 b of the bending member 192 which is aligned with a hole of thecushion rubber 115 is used to combine the bending member 192 with thecushion rubber 115.

As illustrated in FIG. 24, the control unit includes 3 wheatston bridgeswhich consist of 3 pairs of front strain gages 181 a-181 b, 182 a-182 b,183 a-183 b having resistance R11, R12, R13 respectively for measuringload with differently located at the front parts L1,L2,L3 of the trackbelt 111 and 3 pairs of rear strain gages 171 a-171 b, 172 a-172 b, 173a-173 b having resistance R01, R02, R03 respectively for measuring loadwith located at the same rear part of the track belt 111 wherein thepair of the front strain gages 181 a-181 b, 182 a-182 b, 183 a-183 bface each other in each of the wheatston bridges and the pair of therear strain gages 171 a-171 b, 172 a-172 b, 173 a-173 b face each otherin each of the wheatston bridges. Also, the control unit includes anamplifier for amplifying the bride voltage ΔV1, ΔV2, ΔV3 between each offirst points 161 a, 162 a, 163 a and each of second points 161 b, 162 b,163 b which is placed between the front strain gages 181 a, 181 b, 182a, 182 b, 183 a, 183 b and the rear strain gages 171 a, 171 b, 172 a,172 b, 173 a, 173 b, an analog-digital converter for converting theamplified analog bridge voltage into digital bridge voltage for signalprocessing. That is, the control unit controls the driving unit 112 a toaccelerate or to decelerate the rotation of the rollers 112 therebycontrolling the proceeding speed of the track belt 111.

At this time, when power voltage V is applied to each of the wheatstonbridge circuits, each of the bridge voltages ΔV1, ΔV2, ΔV3 between eachof the first points 161 a, 162 a, 163 a and each of the second points161 b, 162 b, 163 b is expressed as the fore-mentioned equations 2 to 4.

Therefore, when a user is biasedly located at the front part or the rearpart of the track belt 111, the resistance of the strain gages installedat which the user is biasedly located is greater than one at which theuser is not biasedly located. Therefore, the sign of bridge voltage ΔV1,ΔV2, ΔV3 is converted by whether the user is biasedly located at thefront part or at the rear part of the track belt 111. Further, as theuser is more biasedly located at any part of the track belt 111, theamount (i.e., absolute value) of the bridge voltage ΔV1, ΔV2, ΔV3becomes greater, therefore, the degree of acceleration or decelerationis determined in proportion to the amount of the bridge voltage ΔV1,ΔV2, ΔV3.

Herein, the front strain gages 181 a, 181 b, 182 a, 182 b, 183 a, 183 band the rear strain gages 171 a, 171 b, 172 a, 172 b, 173 a, 173 b areformed as having all the same resistance.

However, any value of resistance such as 120Ω or 350Ω is acceptable.

Below, referring to FIG. 25, the operation principle of the automaticspeed control apparatus of the third embodiment in accordance with thepresent invention is to be explained.

Firstly, the allowable range of a user's bias not to change theproceeding speed of the track belt is stored and preset in a form of theconverted bridge voltage ΔVset (i.e., initial preset voltage) in thecontrol unit. Herein, the initial preset voltage ΔVset is set based onthe average value of each of bridge voltages ΔV1, ΔV2, ΔV3.

Thereafter, when a user gets on the treadmill and pushes a start buttonon the control panel 121 to walk or run on the track belt, withoutautomatically changing the speed of the track belt 111 for about 10seconds to 60 seconds, the load sensor module 190 measures the loads viathe deck 113 from the user both at front part of the track belt 111 andat the rear part of the track belt 111, whereby the user's propensity onwhether the user likes to exercise at a little bit front part or rearpart of the track belt 111 can be grasped. Concretely, for about oneminute right after starting an exercise, average voltage of the measuredbridge voltages ΔV1, ΔV2, ΔV3 of the wheatston bridges illustrated inFIG. 24 is stored as a reference bridge voltage ΔVref which is acriterion whether to change the proceeding speed of the track belt 111or not.

Thereafter, when the user runs faster and becomes biasedly located atfront part of the track belt 111, as the bending member 192 at theforefront part thereof is deflected more than other ones at the frontpart thereof, the resistance R11 of the forefront strain gages 181 a,181 b becomes greatest, however, the resistance R01, R02, R03 of therear strain gages 171 a, 171 b, 172 a, 172 b, 173 a, 173 b is littlechanged because the bending member 192 at the rear part thereof islittle bent. Therefore, according to the equations 2 to 4, the sign ofthe bridge voltage ΔV1, ΔV2, ΔV3 becomes minus (−), and the absolutevalue of the bridge voltage ΔV1, ΔV2, ΔV3 becomes greater as the user ismore biasedly located on the track belt 111. That is, the absolute valueof ΔV1 becomes greater than the absolute value of ΔV3. At this time, ifthe average value of ΔV1, ΔV2, ΔV3 is put as ΔVavg, when the absolutevalue of ΔVavg−ΔVref exceeds the initial preset voltage ΔVset, as thedegree of the user's front bias exceeds the initial preset degree, eventhough any signal to accelerate is not input from the user, the controlunit controls the proceeding speed of the track belt 111 to beaccelerated in proportion to the absolute value of ΔVavg−ΔVref.

Similarly, when the user runs slower and becomes biasedly located at therearer part of the track belt 111, as the bending member 192 at theforefront part thereof is deflected less than other ones at the frontpart thereof, the resistance R11 of the forefront strain gages 181 a,181 b becomes smallest. Further, although the resistance R13 of thefront strain gages 183 a, 183 b becomes smaller less than that of theforefront strain gages 181 a, 181 b because the bending member 192 atthe rearest one of the front parts thereof is relatively more bent thanthat 192 at the forefront part thereof however is the relatively lessbent comparing when the user stays in the center (i.e., morespecifically, the preset range which does not cause the change of theproceeding speed of the track belt) of the track belt. Therefore,according to the equations 2 to 4, the sign of the bridge voltage ΔV1,ΔV2, ΔV3 becomes plus (+), and the absolute value of the bridge voltageΔV1, ΔV2, ΔV3 becomes greater as the user is more biasedly located onthe track belt 111. At this time, when the absolute value of ΔVavg−ΔVrefexceeds the initial preset voltage ΔVset, as the degree of the user'srear bias exceeds the initial preset degree, even though any signal todecelerate is not input from the user, the control unit controls theproceeding speed of the track belt 111 to be decelerated in proportionto the absolute value of ΔVavg−ΔVref.

Herein, the degree of acceleration or deceleration of the track belt 111is set based on the absolute value of ΔV1−ΔVref or ΔV3−ΔVref.

On the other hand, instead of controlling the proceeding speed of thetrack belt based on the average voltage ΔVavg of averaging all bridgevoltages ΔV1, ΔV2, ΔV3, when the circuit has more than 3 wheatstonbridges, excluding wheatston bridges including the forefront strain gageand/or the rearest strain gage, based on the average voltage ofaveraging the rest of bridge voltages, the track belt can be controlledto be accelerated or decelerated. In this case, the degree ofacceleration or deceleration of the track belt 111 is set based on theabsolute value of a difference between a bridge voltage having asecondly forefront strain gage and the reference bridge voltage or adifference between a bridge voltage having a secondly rearest straingage and the reference bridge voltage.

Herein, whether to accelerate or to decelerate the proceeding speed ofthe track belt is determined by the sign of ΔVavg−ΔVref.

The automatic speed control continues until the user stops the exercise.

INDUSTRIAL APPLICABILITY

As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described embodiments are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the metes and bounds of theclaims, or equivalence of such metes and bounds are therefore intendedto be embraced by the appended claims.

That is, the exemplary embodiment of present invention has explainedwith two strain gages as a pair formed to at least one side of the frontor the rear part of the track belt. However, the present invention alsoincludes a track belt formed with strain gage on the left side and theright side of the front part and the left side and right side of therear part respectively.

Also, the exemplary embodiment includes a load sensor module locatedbetween a deck 113 and a frame 114, but the present invention also cancalculates a load from a different amount of the frame 114 by attachinga strain gage to a

shaped deck support 114 a of the frame 114 as a manner of user'slocation measurement.

As for sensing the user's location on the track, a step to catch user'sexercise location suited to his or her tastes has been included, howeverthis step can be excluded and, instead, the amount and the sign ofbridge voltage difference ΔV can be used for the direct control of thespeed of a track belt 111. In order to avoid excessive sensibility fordeciding accelerating or decelerating, a treadmill of the presentinvention keeps initial value ΔVset without changing the speed when theabsolute value ΔV of the said bridge voltage difference is less than aspecific value, but it can be selectively applied. In this case, as thetrack belt is accelerated or decelerated in the condition of ΔVset andΔV with having no initial value, the speed of the track belt iscontrolled by the absolute value of ΔV and the sign.

1. A speed control apparatus for a treadmill including a deck, a trackbelt of endlessly rotating on the upper and the bottom face of the deck,and a driving unit for driving the track belt comprising: at least onefront load sensor in the front part of the track belt for measuring loadtransferred via the deck which supports the user on the track belt; andat least one rear load sensor in the rear part of the track belt formeasuring load transferred via the deck which supports the user on thetrack belt; wherein the location of the user on the track belt is sensedas being more biasedly located at the front part, as the measured valueby the front load sensor is larger than the measured value by the rearload sensor; and wherein the location of the user on the track belt issensed as being more biasedly located at the rear part, as the measuredvalue by the rear load sensor is larger than the measured value by thefront load sensor, and wherein the speed of the track belt is controlledin accordance with the location of the user on the track belt.
 2. Thespeed control apparatus as claimed in claim 1, wherein the track belt isaccelerated when the user locates at the front part of the track belt,and the track belt is decelerated when the user locates at the rear partof the track belt.
 3. The speed control apparatus as claimed in claim 1,wherein the deck is supported at its both sides on the deck supportswhich is protruded from a frame of the treadmill; and wherein the frontload sensor and the rear load sensor are located at the deck support formeasuring the loads transferred via the deck.
 4. The speed controlapparatus as claimed in claim 1, wherein the front load sensor and therear load sensor are formed as at least one load cell respectively.
 5. Aspeed control apparatus for a treadmill including a deck, a track beltof endlessly rotating on the upper and the bottom face of the deck, anda driving unit for driving the track belt comprising: at least one frontstrain gauge in the front part of the track belt for being deformed bythe load transferred via the deck which supports the user on the trackbelt; and at least one rear strain gauge in the rear part of the trackbelt for being deformed by the load transferred via the deck whichsupports the user on the track belt; wherein the front strain gauge andthe rear strain gauge comprises at least one wheatston bridge circuit;wherein the location of the user on the track belt is sensed by thebridge voltage of the wheatston bridge; and wherein the speed of thetrack belt is controlled in accordance with the location of the user onthe track belt.
 6. The speed control apparatus as claimed in claim 5,wherein the rear strain gauge and the front strain gauge have sameresistance with each other.
 7. The speed control apparatus as claimed inclaim 5, wherein the track belt is accelerated when the user locates atthe front part of the track belt, and the track belt is decelerated whenthe user locates at the rear part of the track belt.
 8. The speedcontrol apparatus as claimed in claim 5, wherein the driving unitcontrols the degree of the acceleration or the deceleration inaccordance with the bridge voltage of the wheatston bridge circuit. 9.The speed control apparatus as claimed in claim 5, wherein the treadmillfurther includes a frame for supporting the deck; and wherein each ofthe front strain gauge and the rear strain gauge is attached on thesurface of one of bending members which are protruded from the frame forsupporting the deck so that the each of the strain gauges is integrallydeformed with the each of the bending members.
 10. The speed controlapparatus as claimed in claim 8, wherein the allowable range of a user'sbias not to change the speed of the track belt is stored and preset in aform of the initial preset voltage ΔVset; and wherein the speed of thetrack belt is changed only when the absolute value of the bridge voltageexceeds the absolute value of the initial preset voltage ΔVset.
 11. Thespeed control apparatus as claimed in claim 10, wherein the averagedvalue of the measured bridge voltage ΔV of the wheatston bridge for apredetermined period right after starting an exercise is stored as areference bridge voltage ΔVref, and wherein the speed of the track beltis changedly controlled by the difference between the bridge voltage ΔVand the reference bridge voltage ΔVref.
 12. The speed control apparatusas claimed in claim 11, wherein the speed of the track belt is changedlycontrolled only when the absolute difference (ΔV−ΔVref) between thebridge voltage ΔV and the reference bridge voltage ΔVref exceeds theinitial preset voltage ΔVset.
 13. A speed control apparatus fortreadmill including a deck, a track belt of endlessly rotating on theupper and the bottom face of the deck, and a driving unit for drivingthe track belt comprising: an accelerating area set at the front part onthe track belt for accelerating the speed of the track belt when a useris located at the accelerating area; a decelerating area set at the rearpart on the track belt for decelerating the speed of the track belt whenthe user is located at the decelerating area; at least one front loadsensor in the front part of the track belt for measuring loadtransferred via the deck which supports the user on the track belt; andat least one rear load sensor in the rear part of the track belt formeasuring load transferred via the deck which supports the user on thetrack belt; wherein the location of the user is sensed by comparing themeasured values from the front load sensor and of the rear load sensor,and thus, the track belt is accelerated when the user is on theaccelerating area and the track belt is decelerated when the user is onthe decelerating area.
 14. The speed control apparatus as claimed inclaim 13, further comprising: a constant speed area set at the middlepart on the track belt for maintaining the speed of the track belt atthe time when the user reaches the constant speed area.
 15. The speedcontrol apparatus as claimed in claim 13, wherein the accelerating areaand the decelerating area are divided into plural areas respectively,and the acceleration of the divided areas and the deceleration thereofare set differently with one another.
 16. The speed control apparatus asclaimed in claim 13, wherein the speed of the track belt is acceleratedwhile the user moves forward although the user is not located at theaccelerating area; and wherein the speed of the track belt isdecelerated while the user moves backward although the user is notlocated at the decelerating area.
 17. The speed control apparatus asclaimed in claim 13, wherein the speed of the track belt is firstlycontrolled by the user's movement, and then, the speed of the track beltis secondly controlled by the user's location.
 18. The speed controlapparatus as claimed in claim 13, wherein the values measured by thefront load sensor and the rear load sensor are averaged for apredetermined unit time.
 19. The speed control apparatus as claimed inclaim 18, wherein in case that the difference between averaged measuredvalues in accordance with the time becomes lower than the predeterminedvalue; and wherein the speed of the track belt is decelerated for aninstance when the speed of the track belt is being accelerated; and thespeed of the track belt is accelerated for an instance when the speed ofthe track belt is being decelerated.
 20. The speed control apparatus asclaimed in claim 18, wherein in case that the difference betweenaveraged measured values in accordance with the time becomes lower thanthe predetermined value; the acceleration degree of the track belt islowered for an instance when the speed of the track belt is beingaccelerated; and the deceleration degree of the track belt is loweredfor an instance when the speed of the track belt is being decelerated.